<!DOCTYPE html>
<html lang="zh-cn">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>太极</title>
    <style>
        *{margin: 0;padding: 0;list-style-type: none;}
        .taiji{
            width: 300px;
            height: 300px;
            border-radius: 50%;
            margin: 50px auto;
            box-shadow: 0 0 0 1px rgba(0, 255, 255, 0.299);

            background: 
            radial-gradient(
                25% 25% at center 25%,
                white 25%,
                black 25%,black 100%,
                transparent 100%
            ),
            radial-gradient(
                25% 25% at center 75%,
                black 25%,
                white 25%,white 100%,
                transparent 100%
            ),
            linear-gradient(
                to right,
                black 50%, 
                white 50%
            );
        }
    </style>
</head>
<body>
    <div class="taiji">

    </div>
</body>
</html>